In order to meet the requirements of strict emission legislation and in order to save fuel consumption fluid injectors, in particular fuel injectors for internal combustion engines, are arranged in a cylinder head of the internal combustion engine in a way, that they inject the fuel directly into a combustion chamber of the engine. In order to get a very fine atomization of the fluid in such applications it is necessary to provide the fluid under high pressure. In gasoline internal combustion engines the fluid pressure may reach up to 200 bars, in diesel engines fluid pressure may reach up to 2000 bars.
WO 03/016707 A1 discloses a fluid injector with a connector to a fuel supply, a housing, an actuator unit and a valve body. The housing is double tubed and has a recess, which takes in the actuator unit. The actuator unit comprises a piezoelectric actuator, which acts on the needle. Between the walls of the double tube-shaped housing the fuel is lead from the connector to a fuel inlet of the valve body. The valve body has a housing part with a recess, that takes in the needle. Depending on the position of the needle, which is of an outward-opening type, a nozzle is opened or closed and respectively fuel is injected or not.
Increasingly strict legislation concerning emissions of internal combustion engines, where a valve body or a fluid injector with a valve body is arranged, makes it necessary to put a lot of effort in measures that reduce the emissions. Very important for the prevention of exhaust emissions is that the fluid injectors used for the internal combustion engine can be controlled in a closed position of the needle, in which a fuel leakage is very low.